It is necessary to inspect a pattern on a semiconductor wafer, formed in a semiconductor manufacturing process, to find out whether or not the pattern is formed as designed. Accordingly, there has since been developed a critical dimension SEM that is a scanning electron microscope with addition of a function for measuring dimensions of a pattern, thereby calculating features such as a pattern width, respective diameters of contact holes, roughness, and so forth, on the basis of image signals (refer to, for example, JP-A-2004-247394, and US2004/0156223A). Further, there have been practiced not only observation of an image, by use of the scanning electron microscope, but also automatic pickup, and classification of the image having various defects such as a pattern open, a pattern bridge, scratch, particle, and so forth, by use of a review SEM with addition of a function for determining the features of the image with the use of a computer. Still further, there has also been practiced fixed-point observation of critical parts of a semiconductor pattern, by use of the review SEM, to thereby display an image as picked up, and execute quantification of the quality of the pattern by calculating the features of the image. Furthermore, as progress is made in the miniaturization of the pattern, it has since been required to speedily, accurately, and simply calculate a quantitative value of the quality, including a three-dimensional shape such as the sidewall of the pattern, and the sidewall of each of the contact holes.
However, with a conventional technology, since the features of an image are calculated by use of only an image formed by secondary electrons ejected from a direction vertical to a wafer, it has been difficult to turn three-dimensional information such as the sidewall of the pattern, and the sidewall of each of the contact holes into an image, and even if imaging thereof is possible, it has been impossible to find the quantitative value of the quality.